Marshall Billingslea, a former Pentagon and NATO official, wanted the information for his boss, Michael Flynn, who had been tapped by Trump to serve as White House national security adviser. Billingslea knew Flynn would be speaking to Kislyak, according to two former Obama administration officials, and seemed concerned Flynn did not fully understand he was dealing with a man rumored to have ties to Russian intelligence agencies.

…

In the following weeks, the Obama White House would grow deeply distrustful of Trump’s dealing with the Kremlin and anxious about his team’s ties. The concern — compounded by surge of new intelligence, including evidence of multiple calls, texts and at least one in-person meeting between Flynn and Kislyak — would eventually grow so great Obama advisers delayed telling Trump’s team about plans to punish Russia for its election meddling. Obama officials worried the incoming administration might tip off Moscow, according to one Obama advisor.

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… In late December, as the White House prepared to levy sanctions and oust Russians living in the in the U.S. in retaliation for the hacks, Obama officials did not brief the Trump team on the decision until shortly before it was announced publicly. The timing was chosen in part because they feared the transition team might give Moscow lead time to clear information out of two compounds the U.S. was shuttering, one official said.

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… After learning that highly sensitive documents from a secure room at the transition’s Washington headquarters were being copied and removed from the facility, Obama’s national security team decided to only allow the transition officials to view some information at the White House, including documents on the government’s contingency plans for crises.

These are, apparently, more of the kinds of evidence we may learn from Sally Yates and John Clapper in their testimony to the Senate Judiciary Committee.